Implantable infusion devices including apparatus for confirming side port access

ABSTRACT

Implantable infusion devices and systems with side port access detection capability and methods of detecting side port access.

BACKGROUND OF THE INVENTIONS

1. Field of Inventions

The present inventions relate generally to implantable infusion devices.

2. Description of the Related Art

Implantable infusion devices have been used to provide patients with amedication or other substance (collectively “infusible substance”) andfrequently include a reservoir and a pump. The reservoir is used tostore the infusible substance and, in some instances, implantableinfusion devices are provided with a refill port that allows thereservoir to be transcutaneously filled (and/or re-filled) with ahypodermic needle. The reservoir is coupled to the pump, which is inturn connected to an outlet port. A catheter, which has an outlet at thetarget body region, may be connected to the outlet port. As such,infusible substance from the reservoir may be transferred from thereservoir to the target body region by way of the pump and catheter.

Implantable infusion devices may also include a side port thatfacilitates access to the outlet port and catheter. The side port, whichis typically accessed by way of a hypodermic needle, allows theclinician to push fluid into the catheter or draw fluid from thecatheter to check for catheter occlusion, sample cerebrospinal fluid(CSF), inject contrast dye into the patient and/or catheter for useduring a fluoroscopic procedure, remove medication from the catheterprior to dye injection, inject additional medication into the targetregion at the catheter outlet and/or remove pharmaceuticals or otherfluids that are causing an allergic or otherwise undesirable biologicreaction. The side port is frequently located at the outer perimeter ofthe infusion device in order to increase the likelihood that the sideport will be tactilely distinguished from the refill port.

Accessing the side port with a hypodermic needle can, however, bedifficult. For example, the outer perimeter location of the side portcan make access difficult and, in those instances where the patient isobese, it can be difficult to tactilely distinguish the side port fromthe refill port. As a result, clinicians may incorrectly determine thatthe refill port has been accessed, when in fact the side port has beenaccessed, and vice versa. Such incorrect access determinations can leadto refill medication being delivered to the side port instead of therefill port and/or contrast dye being delivered to the refill portinstead of the side port. Incorrect access determinations can also leadto medication and contrast dye being delivered to the wrong locationwithin the patient's body when no port is accessed, e.g. to pump pocketinstead of to the region near the catheter outlet. Incorrect side portaccess determinations can also result in an unfounded catheter patencyverification. In the exemplary context of medication delivery to theintrathecal space, the clinician may draw a clear fluid (e.g. serousfluid from the abdomen) into a syringe when side port has not beenproperly accessed. The clear fluid may be mistaken for CSF from theintrathecal space which, in turn, may lead the clinician to determinethat a catheter is not blocked without actually having drawn fluid fromthe catheter.

Accordingly, the present inventors have determined it would be desirableto provide the clinician with confirmation that the side port has beensuccessfully accessed.

SUMMARY OF THE INVENTIONS

The present apparatus and methods employ pressure measurements toconfirm that a side port has been accessed. In one implementation, thepresent apparatus and methods use a pressure sensor associated with theoutlet port, which may also be used to detect catheter blockages, todetect side port access. As such, the present apparatus and methodsconfirm side port access without requiring the use of additional sensorsor other structural elements that would be used solely for the purposeof confirming side port access.

The above described and many other features of the present inventionswill become apparent as the inventions become better understood byreference to the following detailed description when considered inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed descriptions of exemplary embodiments will be made withreference to the accompanying drawings.

FIG. 1 is a plan view of an implantable infusion device in accordancewith one embodiment of a present invention.

FIG. 2 is a plan view of the implantable infusion device illustrated inFIG. 1 with the cover removed.

FIG. 3 is a partial section view taken along line 3-3 in FIG. 1.

FIG. 4 is a block diagram of the implantable infusion device illustratedin FIGS. 1-3.

FIG. 5 is a plan view of an implantable infusion device system inaccordance with one embodiment of a present invention.

FIG. 6 is a block diagram of the implantable infusion device systemillustrated in FIG. 5.

FIG. 7 is a flow chart illustrating a method in accordance with oneembodiment of a present invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The following is a detailed description of the best presently knownmodes of carrying out the inventions. This description is not to betaken in a limiting sense, but is made merely for the purpose ofillustrating the general principles of the inventions. The presentinventions are also not limited to the exemplary implantable infusiondevice described herein and, instead, are applicable to otherimplantable infusion devices that currently exist or are yet to bedeveloped.

One example of an implantable infusion device in accordance with apresent invention is generally represented by reference numeral 100 inFIGS. 1-4. As used herein, an “implantable infusion device” is a devicethat includes a reservoir and an outlet, and is sized, shaped andotherwise constructed (e.g. sealed) such that both the reservoir andoutlet can be simultaneously carried within the patient's body. Theexemplary infusion device 100 includes a housing 102 (e.g. a titaniumhousing) with a bottom portion 104, an internal wall 106, and a cover108. An infusible substance (e.g. medication) may be stored in areservoir 110 that is located within the housing bottom portion 104. Thereservoir 110 may be replenished by way of a refill port 112 thatextends from the reservoir, through the internal wall 106, to the cover108. A hypodermic needle (not shown), which is configured to be pushedthrough the refill port 112, may be used to replenish the reservoir 110.

A wide variety of reservoirs may be employed. In the illustratedembodiment, the reservoir 110 is in the form of a titanium bellows thatis positioned within a sealed volume defined by the housing bottomportion 104 and internal wall 106. The remainder of the sealed volume isoccupied by propellant P, which may be used to exert negative pressureon the reservoir 110. Other reservoirs that may be employed in thepresent infusion devices include reservoirs in which propellant exerts apositive pressure. Still other exemplary reservoirs include negativepressure reservoirs that employ a movable wall that is exposed toambient pressure and is configured to exert a force that produces aninterior pressure which is always negative with respect to the ambientpressure.

The exemplary ambulatory infusion device 100 illustrated in FIGS. 1-4also includes a fluid transfer device 114. The inlet of a fluid transferdevice 114 is coupled to the interior of the reservoir 110 by apassageway 116, while the outlet of the fluid transfer device is coupledto an outlet port 118 by a passageway 120. Operation of the fluidtransfer device 114 causes infusible substance to move from thereservoir 110 to the outlet port 118. A catheter 122 may be connected tothe outlet port 118 so that the infusible substance passing through theoutlet port will be delivered to a target body region in spaced relationto the infusion device 100 by way of the outlet 124 at the end of thecatheter.

A wide variety of fluid transfer devices may be employed. In theillustrated embodiment, the fluid transfer device 114 is in the form ofan electromagnet pump. The present inventions are not, however, limitedto electromagnet pumps and may include other types of fluid transferdevices. Such devices include, but are not limited to, otherelectromagnetic pumps, solenoid pumps, piezo pumps, and any othermechanical or electromechanical pulsatile pump. In the exemplary contextof implantable drug delivery devices, and although the volume/strokemagnitude may be increased in certain situations, the fluid transferdevices will typically deliver about 1 microliter/stroke, but may bemore or less depending on the particular fluid transfer device employed.Additionally, although the exemplary fluid transfer device 114 isprovided with internal valves (e.g. a main check valve and a bypassvalve), valves may also be provided as separate structural elements thatare positioned upstream of and/or downstream from the associated fluidtransfer device.

Energy for the fluid transfer device 114, as well for other aspects ofthe exemplary infusion device 100, is provided by the battery 126illustrated in FIG. 2. In the specific case of the fluid transfer device114, the battery 126 is used to charge one or more capacitors 128, andis not directly connected to the fluid transfer device itself. Thecapacitor(s) 128 are connected to an electromagnet coil in the fluidtransfer device 114, and disconnected from the battery 126, when theelectromagnet coil is being energized, and are disconnected from theelectromagnet coil and connected to the battery when the capacitor(s)are being recharged and/or when the fluid transfer device is at rest.The capacitor(s) 128 are carried on a board 130. A communication device132, which is connected to an antenna 134, is carried on the same sideof the board 130 as the capacitor(s) 128. The exemplary communicationdevice 132 is an RF communication device. Other suitable communicationdevices include, but are not limited to, oscillating magnetic fieldcommunication devices, static magnetic field communication devices,optical communication devices, ultrasound communication devices anddirect electrical communication devices.

A controller 136 (FIG. 4), such as a microprocessor, microcontroller orother control circuitry, is carried on the other side of the board 130.The controller controls the operations of the infusion device 100 inaccordance with instructions stored in memory 138 and/or provided by anexternal device (e.g. the remote control 200 described below) by way ofthe communication device 132. For example, the controller 136 may beused to control the fluid transfer device 114 to supply fluid to thepatient in accordance with, for example, a stored basal deliveryschedule or a bolus delivery request. The controller 136 may also beused to monitor sensed pressure in the manner described below.

Referring to FIGS. 1, 2 and 4, the exemplary infusion device 100 is alsoprovided with a side port 140 that is connected to the passageway 120between the outlet of the fluid transfer device 114 and the outlet port118. The side port 140 facilitates access to an implanted catheter 122,typically by way of a hypodermic needle. For example, the side port 140allows clinicians to push fluid into the catheter 122 and/or draw fluidfrom the catheter for purposes such as checking catheter patency,sampling CSF, injecting contrast dye into the patient and/or catheter,removing medication from the catheter prior to dye injection, injectingadditional medication into the region at the catheter outlet 124, and/orremoving pharmaceuticals or other fluids that are causing an allergic orotherwise undesirable biologic reaction.

The outlet port 118, a portion of the passageway 120, the antenna 134and the side port 140 are carried by a header assembly 142. The headerassembly 142 is a molded, plastic structure that is secured to thehousing 102. The housing 102 includes a small aperture through whichportions of the passageway 120 are connected to one another, and a smallaperture through which the antenna 134 is connected to the board 130.

The exemplary infusion device 100 illustrated in FIGS. 1-4 also includesa pressure sensor 144 that is connected to the passageway 120 betweenthe outlet of the fluid transfer device 114 and the outlet port 118. Assuch, the pressure sensor 144 senses the pressure at the outlet port 118which, in the illustrated embodiment, is also the pressure within thecatheter 122. The pressure sensor 144 is connected to the controller 136and may be used to analyze a variety of aspects of the operation of theexemplary implantable infusion device 100. For example, pressuremeasurements may be used to determine whether or not the fluid transferdevice 114 is functioning properly and whether or not there is acomplete or partial blockage in the catheter 122. Pressure measurementsmay also be used to determine whether or not the side port 140 has beenaccessed, as is described below with reference to FIG. 7. The controller136 may perform a variety of different functions in response todetermination that the fluid transfer device 114 is not functioningproperly, the catheter 122 is blocked, and/or the side port 140 has beenaccessed. For example, the controller 136 may actuate an audible alarm148 that is located within the housing 102 in order to signal that thefluid transfer device 114 is not functioning properly, the catheter 122is blocked, and/or that the side port 140 has been accessed.

Turning to FIGS. 5 and 6, the exemplary implantable infusion device 100may be included in an infusion device system 10 that also includes aremote control 200 that is not implanted in the patient. The exemplaryremote control 200 includes a housing 202, a touch screen display 204(or other input device, such as a keypad, with or without a separatedisplay), a battery or other power source 206, a controller 208, such asa microprocessor, microcontroller or other control circuitry, memory210, and a communication device 212 (including an antenna if necessary).Although the present inventions are not limited to any particularcommunication device, the exemplary communication device 212 is atelemetry device that transmits an RF signal at a specified frequency.The RF signal may, in some instances, be a carrier signal that carriesbit streams. The communication device 212 is configured to send signalsto and receive signals from the communication device 132 in theimplantable infusion device 100 by way of the antenna 134. Otherexemplary communication devices include oscillating magnetic fieldcommunication devices, static magnetic field communication devices,optical communication devices, ultrasound communication devices anddirect electrical communication devices. In some instances, the remotecontrol may also include an audible alarm 214.

The exemplary remote control 200 may be used to perform a variety ofconventional control functions including, but not limited to, turningthe infusion device ON or OFF and programming various infusion deviceparameters. Examples of such parameters include, but are not limited to,the rate of delivery of a given medication, the time at which deliveryof a medication is to commence, and the time at which delivery of amedication is to end. Additionally, in at least some implementations,the implantable infusion device 100 will transmit signals to the remotecontrol 200. The signals provide status information about the infusiondevice 100 that may be stored in memory 210 and/or displayed on thedisplay 204. Examples of such status information include, but are notlimited to, the state of charge of the battery 126, the amount ofmedication remaining in the reservoir 110, the amount of medication thathas been delivered during a specified time period, and the presence of acatheter blockage. The signals from the infusion device 100 may also beindicative of sensed physiological parameters in those instances wherethe infusion device is provided with physiological sensors (not shown).

The exemplary remote control 200 may also be used to initiate a sideport monitoring procedure that is performed by the infusion device 100.The side port monitoring procedure allows the clinician to accuratelydetermine whether or not the side port 140 has been accessed by, forexample, a hypodermic needle.

Referring to FIG. 7, the remote control 200 may be used to send a sideport monitoring initiation signal to an infusion device 100 that isimplanted within a patient (Step 01). In response to the initiationsignal, the infusion device controller 136 will store the pressurecurrently being sensed by the pressure sensor 144, which is associatedwith the same passageway 120 as the side port 140, as the baselinepressure (Step 02). The infusion device controller 136 will also use thebaseline pressure to calculate one or more threshold pressures againstwhich future pressure measurements will be compared (Step 03) after themonitoring period begins (Step 04). Although infusion devices may beconfigured to only calculate a high threshold pressure or to onlycalculate a low threshold pressure, the exemplary infusion device isconfigured to calculate both high and low threshold pressures.

A high threshold pressure is a pressure that is equal to the baselinepressure plus the magnitude of an expected increase in pressure. Themagnitude should be greater than the pressure generated when the fluidtransfer device delivers fluid, yet low enough that a clinician caneasily generate it by pushing a small volume of fluid (e.g. about 1 mlor less) through a syringe and hypodermic needle and into the side port140. For example, a pressure increase would typically be at least about3 psi. A low threshold pressure, on the other hand, is a pressure thatis equal to the baseline pressure less the magnitude of the expecteddecrease in pressure that would result from a clinician withdrawing asmall volume of fluid (e.g. about 1 ml or less) from the side port 140with a syringe and hypodermic needle by pulling on the syringe. Such apressure decrease would typically be at least about 3 psi. Thesepressure increases and decreases are outside the range of pressureincreases and decreases that could occur during the monitoring period asa result of environmental factors or a catheter blockage, and are withinthe range of pressure increases and decreases that commonly occur duringprocedures that involve the side port 140. As such, it may be assumedthat pressures which meet or exceed the high and low pressure thresholdsare the result of the clinician successfully accessing the side port 140and infusing or withdrawing fluid.

As opposed to the absolute pressure measurements described above, thehigh and low threshold pressures may be differential pressures. Here,the baseline pressure is known, but is not calibrated to an absolutepressure in the manner described above. The baseline pressure mayinstead be set to zero for monitoring purposes. Changes in pressure, andthe magnitudes thereof, are monitored from the zero baseline pressure.The high and low threshold pressures are set as a known magnitude ofchange from the zero baseline pressure, rather than the above-describedsum of the absolute baseline pressure and the pressure change.

The side port monitoring period will typically be an amount of time thatis sufficient to allow the clinician to transcutaneously insert ahypodermic needle into the side port 140 of an implanted infusion device100. The monitoring period may, for example, range from about 1 to 5minutes and may be increased or decreased as desired to suit particularsituations.

It should also be noted here that Step 02 and Step 03 will typically becompleted within about 1 second after the side port monitoringinitiation signal is received by the infusion device 100. As such, Step04 may, alternatively, occur prior to or simultaneously with Step 02 orprior to or simultaneously with Step 03.

So long as the monitoring period has not expired (Step 05), the infusiondevice controller 136 will continue to monitor the current pressuresensed by the pressure sensor 144 (Step 06) as the clinician attempts toinsert the hypodermic needle into the side port 140. The clinician willeither depress or withdraw the syringe plunger when he/she suspects thatthe hypodermic needle has entered the side port 140. Should thecurrently monitored pressure increase to a level that is greater than orequal to the high threshold pressure (Step 07), or decrease to a levelthat is less than or equal to the low threshold pressure (Step 08), thecontroller 136 will actuate the alarm 148 (Step 09), thereby notifyingthe clinician that the hypodermic needle has, in fact, been successfullyinserted into the side port 140. Alternatively, or in addition, thecontroller 136 may initiate communication with the remote control 200that results in actuation of the audible alarm 214 and/or display of a“side port access achieved” message on the display 204. The cliniciancan then perform the intended diagnostic or therapeutic procedure, e.g.pushing fluid into or drawing fluid from the catheter 122 by way of theside port 140 to check for catheter occlusion, sample cerebrospinalfluid (CSF), inject contrast dye into the patient and/or catheter foruse during a fluoroscopic procedure, remove medication from the catheterprior to dye injection, inject additional medication into the targetregion at the catheter outlet 124 and/or remove pharmaceuticals or otherfluids that are causing an allergic or otherwise undesirable biologicreaction. The controller 136 will not, on the other hand, actuate thealarm 148 if the sensed pressure remains between the high and lowthreshold pressures. The side port monitoring will end after theexpiration of the monitoring period (Step 10).

In some implementations, the controller 136 will continue to actuate thealarm 148 so long as the pressure is above the high pressure thresholdor below the low pressure threshold. The controller 136 will alsode-actuate the alarm 148 when the pressure returns to a level that isbetween the high and low threshold pressures. If, for example, theclinician stops pushing on the syringe while contrast dye or additionalmedication is being injected into the patient by way of the side port140, the alarm 148 will be de-actuated, and will not be re-actuatedunless the clinician reinitiates the injection procedure and the needleis in the side port. The alarm 148 will also be de-actuated if thehypodermic needle is inadvertently withdrawn from the side port 140during an injection or withdrawal procedure. Here, the clinician willhave to reinsert the needle into the side port 140, and confirm that theneedle has been successfully inserted, in the manner described above.

In the exemplary implementations described above, the functions ofmonitoring the pressure sensor 144, calculating the threshold pressures,analyzing the sensed pressure, and actuating the alarm 148 are performedby the infusion device controller 136 in combination with instructionsthat are stored in memory 138. In other implementations, some or all ofthese functions may be performed by the remote control 200 and, morespecifically, by the controller 208 in combination with instructionsstored in memory 210. Here, the pressure measurements from the pressuresensor 144 in the infusion device 100 will be transmitted to the remotecontrol 200. For example, and referring to FIGS. 4-6, the clinician maybegin the side port monitoring process by pressing a button on the touchscreen display 204. The remote control 200 will then instruct theinfusion device 100 to begin transmitting signals indicative of thepressure sensed by the sensor 144 to the remote control and to continuetransmitting the signals for a defined period, i.e. the monitoringperiod. The transmission may occur at a frequency of, for example, aboutonce per second. The first pressure signal received by the remotecontrol 200 will be used by the controller 208 to set the baselinepressure and calculate high and low threshold pressures. The controller208 will also compare subsequently received pressure data to the highand low threshold pressures, and actuate the audible alarm 214 and/ordisplay a “side port access achieved” message on the display 204 if thesensed pressure exceeds the high or low threshold pressures during themonitoring period.

Although the inventions disclosed herein have been described in terms ofthe preferred embodiments above, numerous modifications and/or additionsto the above-described preferred embodiments would be readily apparentto one skilled in the art. By way of example, but not limitation, thepresent inventions have application in infusion devices that includemultiple reservoirs and/or outlets. It is intended that the scope of thepresent inventions extend to all such modifications and/or additions andthat the scope of the present inventions is limited solely by the claimsset forth below.

1-8. (canceled)
 9. An implantable infusion device, comprising: ahousing; a reservoir within the housing; a reservoir refill port on thehousing and connected to the reservoir; a pump mechanism located withinthe housing and connected to the reservoir; an outlet port configured tohave a catheter connected thereto; a passageway that connects the outletport to the pump mechanism; a side port on the housing and connected tothe passageway at a location between the pump mechanism and the outletport; a pressure sensor within the housing and connected to thepassageway at a location between the pump mechanism and the outlet port;and means for determining that the side port has been accessed by aneedle based on a decrease in pressure measured by the pressure sensor.10. An implantable infusion device as claimed in claim 9, furthercomprising: a catheter connected to the outlet port.
 11. An implantableinfusion device as claimed in claim 9, wherein the pump mechanismcomprises an electromagnet pump.
 12. An implantable infusion device asclaimed in claim 9, further comprising: means for generating an audibleindication that the side port has been accessed.
 13. An implantableinfusion device as claimed in claim 9, wherein the needle comprises ahypodermic needle.
 14. An implantable infusion device, comprising: ahousing; a reservoir within the housing; a reservoir refill port on thehousing and connected to the reservoir; a pump mechanism located withinthe housing and connected to the reservoir; an outlet port configured tohave a catheter connected thereto; a passageway that connects the outletport to the pump mechanism; a side port on the housing and connected topassageway at a location between the pump mechanism and the outlet port;a pressure sensor within the housing and connected to the passageway ata location between the pump mechanism and the outlet port; an alarm; anda control apparatus adapted to store a pressure sensed by the pressuresensor as a baseline pressure in response to a signal from a remotedevice, calculate a low threshold pressure based on the baselinepressure, and actuate the alarm if a pressure subsequently sensed by thepressure sensor decreases to the low threshold pressure.
 15. Animplantable infusion device as claimed in claim 14, wherein the pumpmechanism comprises an electromagnet pump.
 16. An implantable infusiondevice as claimed in claim 14, wherein the side port is configured toreceive a hypodermic needle.
 17. An implantable infusion device asclaimed in claim 14, further comprising: a catheter connected to theoutlet port. 18-19. (canceled)
 20. An implantable infusion devicesystem, comprising: an implantable infusion device including a housing,a reservoir within the housing, a reservoir refill port on the housingand connected to the reservoir, a pump mechanism located within thehousing and connected to the reservoir, an outlet port configured tohave a catheter connected thereto, a passageway that connects the outletport to the pump mechanism, a side port on the housing and connected tothe passageway at a location between the pump mechanism and the outletport, and a pressure sensor within the housing and connected to thepassageway at a location between the pump mechanism and the outlet port;a remote control adapted to communicate with the implantable infusiondevice; and a control apparatus adapted to determine that the side porthas been accessed by a needle based on a decrease in pressure measuredby the pressure sensor.
 21. An implantable infusion device system asclaimed in claim 20, wherein the control apparatus is adapted to actuatean alarm in response to a determination that the side port has beenaccessed.
 22. An implantable infusion device system as claimed in claim20, wherein the side port is configured to receive a hypodermic needle.23. An implantable infusion device system as claimed in claim 20,further comprising: a catheter connected to the outlet port.
 24. Animplantable infusion device system as claimed in claim 20, wherein theremote control includes the control apparatus.
 25. An implantableinfusion device system as claimed in claim 20, wherein the implantableinfusion device includes the control apparatus.
 26. An implantableinfusion device system as claimed in claim 25, wherein the remotecontrol is adapted to transmit a side port monitoring initiation signalto the implantable infusion device; and the control apparatus is adaptedto store a pressure sensed by the pressure sensor as a baseline pressurein response to the initiation signal, calculate a low threshold pressurebased on the baseline pressure, and determine that the side port hasbeen accessed if a pressure subsequently sensed by the pressure sensordecreases to the low threshold pressure. 27-28. (canceled)